1. Field of the Invention
The present invention relates to an endoscope, and more particularly to a bending tube part of an endoscope for observing and treating the inside or internal organs of a body or of machinery.
2. Description of the Background Art
As shown in FIG. 1, an endoscope 1 includes an operating body 2, a flexible insertion tube 3 and an electric cord 4 to be connected to an electrical plug. The flexible insertion tube 3 includes a flexible tube part 5, a bending tube part 6 connected to the end of the flexible tube part 5, and an end part 7 connected to the end of the bending tube part 6. The end part 7 is provided with treating members such as a charge coupled device (CCD) and so forth. The operating body 2 has an operating knob 8 for flexibly bending the bending tube part 6 in up and down and left and right directions.
In FIG. 2, there is shown a conventional bending tube part 6 of an endoscope 1, which comprises a plurality of ring link members 11 having a tubular form, connected with one another in series through pin members 15. In the ring link members 11, a light guide, electric leads for an image guide, the CCD and the like, tubes for feeding air and water and sucking air, a forceps channel and the like are passed. Usually, the ring link members 11 are covered by a braid and an outer cover. In each ring link member 11, a diameter of one end portion 12 is enlarged so as to fit and receive the other end of another ring link member 11. Each ring link member 11 is integrally provided with four connection projections 13 having a hole and projecting frontwards and rearwards, for instance, two connection projections 13 are connected to left and right sides of one end (e.g., normal diameter end portion) of the ring link member 11 and the other two connection projections 13 are connected to upper and lower sides of the other end (e.g., enlarged diameter end portion 12) of the ring link member 11. The two adjacent ring link members 11 are connected with one another by pivotally connecting the connection projections 13 by using pin members 15 while the normal diameter end portion of one ring link member 11 is fitted in the enlarged diameter end portion 12 of another ring link member 11, resulting in the bending tube part 6 can freely be bent in the up and down and left and right directions.
Each ring link member 11 is also formed with wire guide members 16 having a tubular ring form on the inside wall in the same longitudinal planes where the pin members 15 are aligned, and operating wires 17 are passed through the holes of the wire guide members 16. One end of each of the wires 17 is secured to the ring link member 11 positioned in the front end and the other ends of the wires 17 are connected to the knob 8 of the body 2. Hence, by pulling and slackening out the wires 17 by handling the operating knob 8, the bending tube part 6 can be bent at a desired angle in the desired direction.
However, in the bending tube part 6 of the above described conventional endoscope, the ring link members 11 and the pin members 15 are always contacted with one another with inevitable friction during the pivot motion of the ring link members 11 around the pin members 15 when the bending tube part 6 is bent by operating the knob 8. Thus, unnecessary play or clearance is increased between the ring link members 11 and the pin members 15, and, as a result, the life of the bending tube part 6 becomes short.
Further, when the inside of the internal organs of the body or a limited narrow space in the machinery is observed, the radius of the curvature of the bending tube part 6 is preferably small. However, in the conventional bending tube part, since the bending tube part 6 comprises as a whole a series of uniform joint structure, when the end part 7 connected to the bending tube part 6 is bent even in a small amount, the root portion of the bending tube part 6, i.e., the portion near the flexible tube part 5 is firstly bent. Accordingly, after the part of the bending tube part 5 is contacted with the inside wall of the object to be observed, the positioning of the end part 7 in the desired position becomes difficult. In particular, in the operation within an internal organ of a body, the inside wall of the internal organ is often damaged, and pain caused to a patient.
Further, in the conventional bending tube part 6, since one end portion of each ring link member 11 is enlarged and the ring link members 11 are pivotally connected to one another through the pin members 15, a complicated fabrication process is required, and a pin connection step of the ring link members 11 is required, which is inconvenient and disadvantageous. Also, the heads of the pin members 15 radially project outwards and inwards, and the outer surfaces of the ring link members 11 and the pin connection portions thereof are not flat. Hence, there are fear and danger that the uneven surface of the bending tube part 6 will damage the inside wall of an internal organ of a body or the like. In the conventional bending tube part described above, the heads of the pin members 15 can contact the wires 17. In order to prevent this contact between the pin member and the wire, the wire guide members 16 are radially shifted inwards, which restricts the effective space within the ring link members 11.